The invention relates to an induction crucible furnace with a refractory lining prepared from a dry ramming material and a sintering agent, as well as a method for its production.
An induction crucible furnaces as known hitherto, the refractory lining in the approximate shape of a crucible is made by inserting a form into the furnace cage, and leaving a vacant space towards the furnace cage. A dry ramming material to which a sintering agent has been added, is filled in situ into the vacant space and compacted by vibration, and after the form has been removed is brought to temperatures causing sintering of the compacted dry ramming material, the form may, however, also be left in the furnace and will then be destroyed. It is of disadvantage therein, that the filling and compacting of the dry ramming compound is a laborious time-consuming procedure which, since the dry ramming material usually consisting of quartz or quartzite, will subject the operating personnel to considerable amounts of silicogenous dust. Relining after the old lining has been worn out, is also a very laborious procedure since the old, worn-out lining must be broken up in laborious, physically strenuous work, and wherein the danger of damage to the coils of the furnace remains present. In order to perform the aforegoing, the furnace must, of course, be cooled-down to a considerable extent.
With so-called crucible melting furnaces it has been known how to introduce prefabricated crucibles into the furnace to be prepared. Herein, however, claybonded graphite crucibles are used, which may be used in induction crucible furnaces only if the furnace is used exclusively for non-ferrous metals, this restriction constituting a disadvantage. Use of prefabricated crucibles consisting of such a material is, for metallurgical reasons, also not possible in induction crucible furnaces that process iron and steel as well. Furthermore, it has also been tried to use prefabricated crucibles in induction crucible furnaces. The former are produced from a ramming material and a sintering agent, and sintered at a location external to the induction furnace. Sintering at a location external to the furnace has proved to be hardly controllable. Until definite full sintering, the quartz of the dry ramming material is undergoing several transformation with strong growing of the granules, processes which are partly reversible, and by which a crucible of this type will be loosened to too great an extent, become fragile and very brittle, so that it can thus hardly be transported or handled.